Watch Bon Iver's Justin Vernon Join Dead & Company in Wisconsin

Bon Iver‘s Justin Vernon joined Dead & Company as a surprise guest Saturday night during the group’s concert at East Troy, Wisconsin’s Alpine Valley; The 22, A Million singer is a native of Eau Claire, Wisconsin.

Vernon joined the jam supergroup for the last three songs of the band’s first set, "Black Muddy River," "Friend of the Devil" and "Bird Song," the latter featuring a lengthy jam punctuated by numerous solos courtesy of Vernon and John Mayer.

"Nbd sitting in with the dead tonight at alpine," Vernon informed fans on Twitter hours before Dead & Company’s second Alpine Valley gig.

Vernon is no stranger to the Grateful Dead’s music as his Eaux Claires Festival hosted an all-star "Day of the Dead" live performance in 2016, a one-off gig celebrating the National-led charity album. The Day of the Dead compilation included Vernon (with his DeYarmond Edison side project and former Dead pianist Bruce Hornsby) covering "Black Muddy River," which Vernon reprised Saturday night.